Necrophos

my suggest :

-Death Pulse : no change
-Ghost Shroud : remove Self Magic Resistance Reduction
-Heartstopper : no change
-Reaper's Scythe : can't kill bosses instead stun them during 3 seconds (?) / remove "Respawn Time Increase"

Legendaries shards :

Death Pulse
-skulls hitting ennemies pop an other pulse one level lesser
-x% chance to cast pulse when attacking and attacked (or loosing life ?)
-skulls hitting allies/self grant avatar during 1 second

Ghost Shroud
-add 40 % magic resistance
-apply on allies and remove disarm
-cast a death pulse at the start and at the end of shroud

Heartstopper
-apply on allies (only positives effects)
-necrophos gain Max Health per Second: 0.6%/1.2%/1.8%/2.4% (apply to allies if 1st heartstopper's shard is picked)
-when hit necrophos has x% chance to cast ghost shroud then cast death pulse (apply to allies if 1st heartstopper's shard is picked only dor death pulse part)

Reaper's Scythe
-x% chance to pop a heart when killing a captain
-can be cast on ally/self to heal by 0.7/0.8/0.9 of the current life
-cast on all target in the range of the spell

Minor shards :

Death Pulse
-increase Aoe
-increase dmg/heal
-reduce cd

Ghost Shroud
-increase Aoe
-increase slow effect
-reduce cd

Heartstopper
-increase Aoe
-increase stack duration
-increase Hp/Mp regen per stack

Reaper's Scythe
-reduce cd
-increase cast range
-increase stun duration

Add more heroes, please! :)